This invention relates to a method for reproducing color separation pictures on a recording film from original pictures, for making color separation printing plates.
In a conventional color scanner, an original color picture is color-separated and color-corrected to obtain color separation picture signals of primary colors such as yellow, magenta, cyan and black, and then the color separation picture signals obtained are stored in a memory. Then the color separation picture signals are read out of the memory, and color separation pictures of the original picture for making color separation printing plates are reproduced on a recording film in its predetermined division areas by using the color separation picture signals.
When the color separation pictures are reproduced in the recording film secured to a recording cylinder, the recording film is covered by a halftone contact screen consisting of four halftone screens with different screen angles for four color inks such as yellow, magenta, cyan and black. The position of the halftone contact screen is properly adjusted on the recording cylinder so that the four halftone screens may exactly be positioned in the predetermined positions. Thus, in practice, it is difficult to change the size of the halftone contact screen, and the size of the recording film is limited depending on the size of the halftone contact screen.
Accordingly, in this case, even if a small original picture is reproduced in the recording film, the recording film still having a space for the reproduction must be processed, which is uneconomical. Further, the recording film exchange operation is carried out carefully in a darkroom by skilled operators, and involves more careful removal and reset operations of the halftone contact screen. In such operations the halftone contact screen is apt to be damaged. Hence, such a film exchange operation should be reduced.
In this embodiment, however, in general, a plurality of original pictures of small size cannot be processed in a single operation, i.e. the color separation reproduction pictures of the plurality of original pictures cannot be recorded on the same recording film because the color correction conditions of each original picture are properly varied depending on the nature of the original picture.